Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
3.1.3.1 Redundant Swap Sequence.
Redundant Mode control process proceeds as follows (Also refer to Figures 3-3 and 3-4):
• Initially, the Main Module is active. The Standby Module remains tri-stated off-line, and its E1
port is looped back onto itself in order to monitor the quality of its own output.
• The Main Module monitors its own on-board and framer states, and notifies the Standby module of
its status.
• The Standby Module monitors the Main Module status and measures bus signals generated by
Main Module.
• The Standby Module monitors its own on-board and framer states. Automatic swap will not be
allowed in the event of a Standby failure.
• If the Standby Module determines that a Main failure has occurred, it forces the Main Module off-
line and takes over multiplexer operation after waiting through a Swap Delay timeout. The actual
detection of the failure can take from tens of microseconds to hundreds of milliseconds, depending
on the frequency of a particular signal.
• When the Standby Main Module is active (on-line), the Main Module remains inactive (tri-stated
and off-line), and its E1 port is looped back onto itself.
• The decision-making process can be overridden by the front-panel mode slide switch on the
Standby Module or by an operator command. Both methods allow forcing either the Main or the
Standby Module to become active. The front panel mode slide switch has precedence over any
software commands. Automatic swap is allowed only if both the switch and the software
commands select “AUTO” mode.
• Automatic swap from Main to Standby is non-revertive. The Main module can be made active
again only by the front panel mode slide switch or by an operator command. There is no automatic
return to Main.
IMUX 2000E1 RFL Electronics Inc.
January 23, 2004 3-4 (973) 334-3100
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